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Cold cylinder exhaust on idle?

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  • Cold cylinder exhaust on idle?

    I got the Torino fired up and with an infrared temp gauge my headers vary wildly in temps.

    Cylinder 4 measures 280F vs the rest are in the 500-600 range. I'd expect some variability between cylinders because it's carbed, but that seems like something could be wrong. Pulled the plug for that cylinder and doesn't seem fouled.

    Setup is a 351W with stock bottom end, 670cfm holley carb, air gap intake, and shorty headers.

    Any suggestions on how to diagnose, or am I chasing something that isn't a real problem?

  • #2
    I'd verify that you have spark on that cylinder. Pull the plug and make sure it isn't fouled. You can check if it's getting spark voltage with a timing light or tach with a conductive pickup.
    David G.
    1969 Mustang Sportsroof
    1998 Mustang V6 Coupe
    2002 Supercrew Lariat
    Mustangsandmore Member # 1964


    • #3
      Gently remove the plug wire while the engine is at should be able to determine a miss.
      If you can't notice a miss, then do as David G suggested and put your timing light on the #4 plug wire and determine if it is firing or not.

      Come back and let us know your progress.... Good Luck!

      Quality means doing it right when no one is looking. - Henry Ford


      • #4
        You may want to test the resistance of that spark plug wire and compare it with the others. You could also swap the plugs and wires around and see if the problem moves.
        '70 Mach 1 - '72 Sprint - '94 F-150 XL -'97 E-150 - '18 Edge SEL AWD

        ”Mercy for the guilty is cruelty to the innocent.” ~ Adam Smith